1. Field of the Invention
The invention relates to a method and to an apparatus for anaerobic digestion of biomasses of different origin, consistency and chemical properties for the production of biogas.
2. Brief Description of the Background of the Invention Including Prior Art
Methods for the production of biogas with a fermenting machine or reactor are known, wherein complex organic materials (lipids, protids, glucids), which materials are contained in plants or in animal residual products, are destroyed and thereby enable to obtain energy by way of chemical reaction with the aid of enzymes, fungi and microorganisms, wherein these are formed in the biomass in the substrate of a biological origin (organic mass) under in each case defined process conditions. The fermentation is performed thanks to a non-aerobic flora of bacteria, which flora of bacteria is formed depending on the temperature prevailing in the fermentation machine. These bacteria are contained in the biomass and strongly multiply in a closed environment, wherein the enzymes serve as a catalyst; the enzymes react with the organic materials mostly to CH4 (methane) and CO2 (carbon dioxide).
The known methods and the plants for their realization do not take sufficiently into consideration that the non-aerobic flora of bacteria is formed of strains of bacteria, which strains of bacteria develop optimally at in each case specific temperatures between 25 degrees centigrade and 45 degrees centigrade and under specific environmental conditions. In addition there exists the risk that a too pronounced acidification occurs during the acidification phase caused by the formation of free acids and therefore the control of the pH value becomes difficult. This causes that the times, within which the individual process steps run, are becoming increased or, respectively, that the residues of the fermentation process are obtained which are not suitable for an advantageous employment of the process, since the residues contain not reacted or only partially reacted components. A too strong acidification can also cause the interruption of the biological course and therewith of the fermentation process. The precedingly recited methods and the corresponding apparatuses do not sufficiently take into consideration the influence of the temperature on the reaction and more generally those of the environmental situations under which the degradation reactions occur. In particular, the conditions for too high an acidification can occur during the phase of the acid formation. The too high formation of free acids and therewith difficult control of the pH values effects a slowing down of the course of the reaction and an incomplete conversion of the substrate with successive maintaining of residual products which are not suitable for later use because of the high content in organic materials.